Helmet strap

ABSTRACT

A strap ( 14,15 ) used in a strap adjuster for a protective helmet is provided. The strap adjuster comprises a case ( 10 ) comprising a front face ( 11 ), a rear face ( 12 ) and a slot ( 13 ) therebetween. Within the slot ( 13 ) are received the ends of the two straps ( 14,15 ), each of which is slotted and defines on one side of the slot ( 13 ) a respective rack gear profiles ( 16,17 ). A control knob ( 18 ) is rotatable in the case ( 10 ) and has one or more pinion gear profiles to engage the respective rack gear profiles ( 16,17 ). Each strap ( 14,15 ) has a mid-portion comprising a plurality of thin strap portions ( 21 ) arranged side-by-side and separated by long apertures ( 22 ) in a direction transverse to the length of the strap ( 14,15 ). The apertures ( 22 ) define the thin strap portions ( 21 ) of increased flexibility, and may he at least partially out of the plane of the strap ( 14,15 ).

TECHNICAL FIELD

This invention relates to a strap for a protective helmet, particularly a cycle or sports helmet.

BACKGROUND TO THE INVENTION

Protective helmets typically comprise a composite plastics shell to cover at least the upper part of the human head. For cost reasons the number of different shell sizes are limited, and thus a helmet is typically oversize and provided with an internal support system which is adjustable to suit the wearer.

A very simple system is provided in e.g. a bump cap for a construction worker, and comprises a flexible strap which is adapted to encircle the head. The effective length of the strap is adjustable at the rear so as to obtain a reasonably comfortable fit. Such a cap may include a separately adjustable net to space the cap from the top of the wearer's head—this may allow increase of ventilation and also serves to provide a cushioning space in the event of an impact on the cap. Adjustable net systems tend to be complex, and difficult to adjust for optimum comfort.

A particular difficulty with sizing helmets for optimum fit is that the human head varies considerably in dimension and shape. Furthermore the head may be asymmetric. A system for fitting a helmet should be able to accommodate a wide variation of size and section whilst ensuring that a comfortable fit can be obtained.

Cycle and sports helmets typically comprise a chin strap in order to ensure that the helmet is not displaced during activity. Such helmets may be worn for extended periods of time, and accordingly comfort is an important feature. In particular the means of sizing the helmet to the wear's head should be effective, simple to operate, and economical to produce.

According to the invention there is provided a flexible helmet strap comprising plural openings along the length thereof, said openings being side by side in a direction transverse to the length of the strap.

Such a strap has increased flexibility in the region of the openings and can better accommodate variations in the size and shape of the wearer's head. In particular the openings permit local bending of the strap to better fit the curvature and angle of the wearer's head.

A strap according to the invention typically has a length of openings appropriate to the head of a typical wearer, and a substantially constant width in the region of the openings. The thickness of the strap is typically a small proportion of the width so as to accommodate bending in the plane of the thickness direction, and may be in the range 10-30% of the width of the unapertured strap adjacent the openings.

In a preferred embodiment the plural openings are defined by multiple strap portions of reduced width. The width of said portions is preferably no more than twice the thickness thereof, and in the preferred embodiment the width of said portions is substantially the same as the thickness thereof. The strap portions may be rectangular in section, or may be arcuate or somewhat rounded.

In the preferred embodiment the strap portions are substantially parallel in the unfitted condition, and are preferably of the same length. The strap portions may be wholly side-by-side or may overlap to some extent. The openings are preferably longer than the width of the strap at the ends of the openings, and in the preferred embodiment are about 5 times as long.

In the preferred embodiment two openings are provided bounded by three strap portions. In use each strap portion can bend to accommodate local head shape so that the openings therebetween may become wider or narrower. Furthermore the strap portions may have different curvatures since they are not constrained to be co-planar.

The strap portions may lie at least partially outside the plane of the strap, when in the unflexed condition, and in the preferred embodiment the middle of three strap portions lies in a different plane at one end only.

Preferably a single set of openings is provided intermediate the ends of a strap according to the invention.

Two straps of the invention may be combined into a strap adjuster mechanism to form an adjustable headband, one strap associated respectively with the left and right sides of the head. The openings are preferably provided to fit over the back lower corners of the skull.

Other features of the invention will be apparent from the following description of a preferred embodiment shown by way of example only, in which:

FIG. 1 is a schematic plan view of a strap adjuster.

FIG. 2 schematically shows the straps of the adjuster of FIG. 1.

FIG. 3 is a sectional view on line 3-3 of FIG. 1.

FIG. 4 is a partial side elevation of the embodiment of FIG. 2.

With reference to FIGS. 1-3, a strap adjuster comprises a case 10 comprising a front face 11, a rear face 12 and a slot 13 therebetween. Within the slot are received the ends of two straps 14, 15, each of which are slotted and define on one side of the slot a respective rack gear profile 16, 17.

A control knob 18 is rotatable in the case 10 and has one or more pinion gear profiles (not shown) to engage the respective rack gear profiles 16, 17.

It will readily be appreciated that since the respective rack gear profiles are on opposite sides of the rotational axis of the control knob 18, rotation in one direction (clockwise as viewed in FIG. 2) will draw the straps into the case, whereas rotation in the opposite direction will move the straps apart.

Such a rotatable strap adjuster is known. The strap adjuster may allow the straps to be pushed into the case for rapid tightening, but permit outward movement only upon rotation of the control knob 18.

In use the case may be mounted in a floating manner between two straps, or may be fixed to an appropriate substrate, such as a helmet. A third strap (not shown) may be provided orthogonally, and in the case of a helmet provide simultaneous adjustment over the top of the head whereas the straps 14, 15 determine tightness around the head. The adjuster is typically located at the back of a helmet.

Each strap 14, 15 has a mid-portion comprising a plurality of thin strap portions 21 arranged side-by-side and separated by long apertures 22. With additional reference to FIG. 4, it can be seen that the strap portions may lie in different planes over part of their extent in the strap length direction.

In particular FIGS. 2 and 4 illustrate three side-by-side strap portions 21, the centremost of which protrudes in a different plane from the outermost at the end adjacent the adjuster. All three strap portions merge in the same plane at the end distant from the adjuster, the arrangement allowing flexibility of all of the strap portions in orthogonal directions transverse to the length of the strap, and represented by arrows A and 13.

The outer ends of the straps 14, 15 comprise plain portions 23 having a means of attachment to another component which is intended in use to be tightened, such as the headband of a helmet or bump cap. As illustrated moulded button projections 24 allow a snap-fitting connection in appropriate holes, but other means of attachment are of course possible.

The flexible helmet strap of the invention comprises the side-by-side strap portions 21. The ends of the straps, in particular the attachment projections 24 and the rack profiles 16, 17 form no part of the present invention.

Typical dimensions of the three strap portions of a strap suitable for a cycle or sports helmet are a length of 26 mm, a cross-sectional area of 1-2 mm², and a minimum separation of about 0.1 mm in the undeformed state in the direction of arrow A and about 1.5 mm in the direction of arrow B.

The strap of the invention is preferably injection moulded of a suitable plastics material, such as nylon PA66. 

1. A flexible helmet strap comprising plural openings along the length thereof, said openings being defined by strap portions lying side-by-side in a direction transverse to the length of the strap.
 2. A strap according to claim 1 wherein said strap portions have substantially the same length.
 3. A strap according to claim 1 or claim 2, wherein said strap portions have a substantially constant. spacing.
 4. A strap according to any preceding claim wherein said strap portions are substantially parallel.
 5. A strap according to claim 4 wherein said strap portions have a substantially constant cross-sectional area.
 6. A strap according to claim 5, wherein said strap portions have a cross-sectional area of less than 2 mm².
 7. A strap according to any of claims 4-6, wherein said strap portions are co-planar at one end thereof.
 8. A strap according to any preceding claim and having three strap portions.
 9. A strap according to any preceding claim and comprising a one-piece plastics moulding.
 10. A strap according to claim 9 of nylon PA66.
 11. A helmet strap assembly comprising two helmet straps according to any of claims 1-10 and a fixing, one end of each strap being adapted for connection to said fixing, and the other end of each strap being adapted for connection to a helmet component.
 12. An assembly according to claim 11, wherein said fixing comprises a means of drawing said straps into closer engagement around the wearer's head.
 13. An assembly according to claim 11 or claim 12 wherein in use said fixing is adapted to lie centrally at the rear of the wearer's head, said strap portions lying in use on either side thereof at the rear base of the skull.
 14. A helmet strap substantially as described herein with reference to the accompanying drawings.
 15. A helmet strap assembly substantially as described herein with reference to the accompanying drawings. 